new file mode 100644
--- /dev/null
+++ b/src/core/ngx_hash.c
@@ -0,0 +1,160 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+
+
+ngx_int_t
+ngx_hash_init(ngx_hash_t *hash, ngx_pool_t *pool, void *names)
+{
+    u_char      *p;
+    ngx_str_t   *n, *bucket;
+    ngx_uint_t   i, key, size, best, *test, buckets, min_buckets;
+
+    test = ngx_alloc(hash->max_size * sizeof(ngx_uint_t), pool->log);
+    if (test == NULL) {
+        return NGX_ERROR;
+    }
+
+    min_buckets = hash->bucket_limit + 1;
+
+#if (NGX_SUPPRESS_WARN)
+    best = 0;
+#endif
+
+    for (size = 1; size < hash->max_size; size++) {
+
+        buckets = 0;
+
+        for (i = 0; i < size; i++) {
+            test[i] = 0;
+        }
+
+        for (n = (ngx_str_t *) names;
+             n->len;
+             n = (ngx_str_t *) ((char *) n + hash->bucket_size))
+        {
+            key = 0;
+
+            for (i = 0; i < n->len; i++) {
+                key += ngx_tolower(n->data[i]);
+            }
+
+            key %= size;
+
+            if (test[key] == hash->bucket_limit) {
+                break;
+            }
+
+            test[key]++;
+
+            if (buckets < test[key]) {
+                buckets = test[key];
+            }
+        }
+
+        if (n->len == 0) {
+            if (min_buckets > buckets) {
+                min_buckets = buckets;
+                best = size;
+            }
+
+            if (hash->bucket_limit == 1) {
+                break;
+            }
+        }
+    }
+
+    if (min_buckets == hash->bucket_limit + 1) {
+        ngx_log_error(NGX_LOG_EMERG, pool->log, 0,
+                      "could not build the %s hash, you should increase "
+                      "either %s_size: %i or %s_bucket_limit: %i",
+                      hash->name, hash->name, hash->max_size,
+                      hash->name, hash->bucket_limit);
+        ngx_free(test);
+        return NGX_ERROR;
+    }
+
+    hash->buckets = ngx_pcalloc(pool, best * hash->bucket_size);
+    if (hash->buckets == NULL) {
+        ngx_free(test);
+        return NGX_ERROR;
+    }
+
+    if (hash->bucket_limit != 1) {
+
+        for (i = 0; i < best; i++) {
+            test[i] = 0;
+        }
+
+        for (n = (ngx_str_t *) names;
+             n->len;
+             n = (ngx_str_t *) ((char *) n + hash->bucket_size))
+        {
+            key = 0;
+
+            for (i = 0; i < n->len; i++) {
+                key += ngx_tolower(n->data[i]);
+            }
+
+            key %= best;
+
+            test[key]++;
+        }
+
+        for (i = 0; i < best; i++) {
+            if (test[i] == 0) {
+                continue;
+            }
+
+            bucket = ngx_palloc(pool, test[i] * hash->bucket_size);
+            if (bucket == NULL) {
+                ngx_free(test);
+                return NGX_ERROR;
+            }
+
+            hash->buckets[i] = bucket;
+            bucket->len = 0;
+        }
+    }
+
+    for (n = (ngx_str_t *) names;
+         n->len;
+         n = (ngx_str_t *) ((char *) n + hash->bucket_size))
+    {
+        key = 0;
+
+        for (i = 0; i < n->len; i++) {
+            key += ngx_tolower(n->data[i]);
+        }
+
+        key %= best;
+
+        if (hash->bucket_limit == 1) {
+            p = (u_char *) hash->buckets + key * hash->bucket_size;
+            ngx_memcpy(p, n, hash->bucket_size);
+            continue;
+        }
+
+        for (bucket = hash->buckets[key];
+             bucket->len;
+             bucket = (ngx_str_t *) ((char *) bucket + hash->bucket_size))
+        {
+            bucket->len &= 0x7fffffff;
+        }
+
+        ngx_memcpy(bucket, n, hash->bucket_size);
+        bucket->len |= 0x80000000;
+    }
+
+    ngx_free(test);
+
+    hash->hash_size = best;
+    hash->min_buckets = min_buckets;
+
+    return NGX_OK;
+}